Estimating demographics associated with a selected geographic area

ABSTRACT

In one embodiment, demographics associated with a selected geographic area may be estimated using visitor demographics. For each mobile device of a plurality of mobile devices, a more recent location estimate of the mobile device determined by a positioning system that is within the selected geographic area may be associated with a previous location estimate of the mobile device determined by the positioning system. Origin geographic areas that include the previous location estimates are determined. Demographics associated with the selected geographic area may be estimated based at least in part on demographics associated with the origin geographic areas of the plurality of mobile devices.

RELATED APPLICATIONS

This application is a continuation of and claims benefit under 35 U.S.C.§120 to U.S. Utility application Ser. No. 14/073,952, entitled Method ofand System for Estimating Temporal Demographics of Mobile Users, filedNov. 7, 2013, which is a a continuation of and claims benefit under 35U.S.C. §120 to U.S. Utility application Ser. No. 13/252,685, entitledMethod of and System for Estimating Temporal Demographics of MobileUsers, filed Oct. 4, 2011, now issued as U.S. Pat. No. 8,606,294 on Dec.10, 2013, which claims the benefit under 35 U.S.C. §119(e) of the U.S.Provisional Application No. 61/389,834, entitled Method of and Systemfor Estimating Temporal Demographics of Mobile Users, filed Oct. 5,2010, the contents of all of which are incorporated by reference herein.

BACKGROUND

1. Field

The invention generally relates to finding temporal demographics ofanonymous mobile users at different locations and, more specifically,the methods of estimating aggregated temporal demographics of anycommunity of mobile users at any location by aggregating short locationsequences (hereafter known as tracks) from individual anonymized users.

2. Description of Related Art

In recent years, the number of mobile and portable computing devices hasincreased dramatically, and at the same time the number oflocation-aware applications for such devices has exploded.

Location-based services (LBS) is an emerging area of mobile applicationsthat leverages the ability of new devices to calculate their currentgeographic positions and report them to a user or to a service. Examplesof these services range from obtaining local weather, traffic updates,and driving directions to child trackers, buddy finders and urbanconcierge services. These new location-aware devices rely on a varietyof technologies that all use the same general concept to generatelocation information. By measuring radio signals originating from knownreference points, these devices can mathematically calculate the user'sposition relative to these reference points.

SUMMARY

Under one aspect of the invention, a method of and system for estimatingtemporal demographics of mobile users is disclosed.

Under another aspect of the invention, a method of estimatingdemographic information associated with a selected geographical areabased on tracks of travel of a plurality of individuals includes, foreach individual of a plurality of individuals, determining a location ofan intermediate ending point of a portion of a track of travel of theindividual. The intermediate ending point of each track being within aselected geographical area. The method also includes, for eachindividual of the plurality of individuals, determining a location of anintermediate starting point of the portion of the track of travel of theindividual. The intermediate starting point being within a startinggeographical area. The method further includes estimating a ratio ofindividuals transiting into the selected geographical area versusindividuals that are residents of the selected geographical area basedon a count of the number of tracks having the intermediate ending pointwithin the selected geographical area. The method also includesestimating demographic information associated with the selectedgeographical area based on the estimated ratio and based on demographicinformation associated with the starting geographical areas.

Under a further aspect of the invention, the estimating the demographicinformation associated with the selected geographical area is furtherbased on demographic information associated with residents of theselected geographical area. Under another aspect of the invention, theestimating the ratio and the estimating the demographic informationassociated with the selected geographical area occurs during adesignated time period.

Under still another aspect of the invention, a method of estimatingdemographic information associated with a selected geographical areabased on a track of travel of at least one individual includes, for atleast one individual, determining a selected geographical area along aportion of a track of travel of the individual and determiningdemographic information associated with the at least one individual. Themethod also includes estimating a ratio of individuals transiting intothe selected geographical area versus individuals that are residents ofthe selected geographical area and estimating demographic informationassociated with the selected geographical area based on the estimatedratio and based on demographic information associated with the at leastone individual.

Under an aspect of the invention, the estimating demographic informationassociated with the selected geographical area is further based ondemographic information associated with residents of the selectedgeographical area.

Under still other aspects of the invention, systems for estimatingdemographic information associated with a selected geographical areabased on a track of travel of at least one individual include logic forperforming the actions recited above. Any of the aspects recited abovecan be combined with any of the other aspects recited above.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of various embodiments of the presentinvention, reference is now made to the following descriptions taken inconnection with the accompanying drawings in which:

FIG. 1 depicts a visual presentation of LBS requests for a portion ofthe city of Boston.

FIG. 2 depicts nanotracks and transitions from different tiles,including the same tile.

FIG. 3 depicts a set of tiles and transition of users from one tile toanother tile, and it shows users aggregate at some points and dispersefrom that point again to other tiles.

FIG. 4 depicts demographics of a tile is divided to two parts, which arehome demographics and visitor demographics.

FIG. 5 depicts an example of transitions of users from differentlocations and different tiles to a given tile.

FIG. 6 depicts an overview of a process for estimating temporaldemographics.

DETAILED DESCRIPTION

As used herein, the term “demographics” means statistical data of apopulation. Demographics or demographic data includes, but is notlimited to age, income, education, race, gender, disabilities, mobility(in terms of travel time to work or number of vehicles available),educational attainment, home ownership, employment status, and etc. Thestatistical data includes average values, mean values, minimum values,maximum values, standard deviance values, and any other statisticalmeasures known to one skilled in the art.

As used herein, the term “track” means a sequence of locations occupiedby a single user and/or device and the times at which they wereoccupied. Thus, a track can represent a path of travel taken by a user.

As used herein, the term “nanotrack” means a portion of a track betweentwo points of the sequence of location estimates that make up the track.A nanotrack can be a repositioning of a user and/or device between twosequential position estimates (or “one hop”), which is the smallestpiece of a track.

As used herein, the term “tile” means a portion of an entiregeographical area of interest. In other words, the entire geographicalarea is divided into multiple tiles. Tiles can be small areas definingthe resolution of demographics analysis. Tiles can be the same sizeeverywhere or they can be different sizes in different places based onthe required demographics resolution. Example of tile size is 400 m by400 m or between 400 m and 2 km. The tile size can be defined based onpopulation, and/or number of users, and/or required resolution in anarea or resolution of available residential demographics, which cancause tile size to vary from one location to another. The tiles can beof any shape, regular or irregular, including, but not limited to, anypolygonal shape, circular, oval, etc. Moreover, the shape and extent ofthe tile can follow political boundaries and can encompass a town, city,county, state, and/or As used herein, the term “time slice” means aportion of a designated amount of time. For example, as describedherein, demographics are calculated for each tile, but demographics canalso be different within a single tile at different times of the day.Therefore, the entire time (e.g. a day) is “sliced” into pieces, likesegments of one hour, or multiples of hours, or a day. Slices of timesegments can be equal or can be different in duration.

As used herein, the term “user” means an LBS user or an individual of acommunity of interest. FIG. 1 shows an example of density of usage at aspecific time in a form of a “heat map” 100, in which a relatively highdensity of users is shown in darker shaded areas 105, a medium densityof users is shown in medium shaded areas 110, and a relatively lowdensity of users are shown in lighter shaded areas 115. As in thisfigure, identity of users are not known and only the density of users atdifferent times are known.

Under one aspect of the invention, the temporal and spatial demographicsof location-based-services (LBS) users are found based on anonymousspatial and temporal density of usage (density of usage quantifies thetemporal frequency of location requests emanating from a particularlocation). It is assumed that the locations of LBS users are knownwithout knowing the users' identities. Although the aggregate of LBSusers at different times and different locations is known, there is nouser's identification included in the location information and,therefore, individual user demographics are not available. Moreover,because of privacy concerns, the “long tracks” of locations of users arenot made available.

Preferred embodiments of the invention provide a method to find theabove described demographics by defining a system, which is initializedwith aggregate demographics describing the residents of each tile foreach time slice which are supplied by a third party such as the U.S.Census Bureau. Then nanotracks are used to extract time-varyingdemographics caused when users travel outside of the tiles in which theyreside. Specifically, a nanotrack leaving a particular tile representsan abstracted individual whose demographics are the average of theorigin tile at the moment when the track left the tile. There is nodifferentiation between users within a given tile at a given time, sousers retain anonymity. Anonymity can be defined as K-anonymity, whichmeans only tiles with more than K number of users at a given time sliceis considered in the system.

The location of the LBS user is determined using any positioningtechnology or methodology, e.g., satellite based positioning systems(for example GPS or Galileo), WiFi positioning systems, cell positioningsystems, a hybrid satellite-based and WiFi-based positioning system,and/or entered manually.

In general, this aspect of the invention enables one to find temporaldemographics of a community at different locations, in which theaggregate of the density of the members of a community in differentlocations and at different times is known. In other words, temporaldemographics of a community at different locations are found based onthe demographic of the community from different places and at differenttimes. The aggregate location of members of the community is knownwithout knowing the demographics of individual members. There is also notrack of individual members of the community, from which demographics ofindividual users can be extracted. In other words, each location showsthat a member of the community was in that location at that time withoutknowing exactly which user.

Extended Location:

Under another embodiment, the current location of a user is associatedwith a previous location of the user. A user's previous location refersto the last time that the location of the user was determined, and insome implementations, it is the location associated with the most recenttime that the user used LBS. By doing this, both the current location ofa user and the time of usage are known to the system as well as theprevious location of the user at the corresponding time.

In one implementation, associating a previous location with a currentlocation is done on the user's device. In other implementations, theaforementioned associating actions occur on a location server. Theuser's device can associate the current location with the previouslocation, or the user can have a unique user identification only for ashort period time, and the user identification will change afterexpiration of a defined period. In this case, the user's track for theperiod of time during which the unique identification was used is knownto the system. During this time, the recorded track information willinclude one or more locations records. Even in this usage scenario,users are still anonymous, and only the current location (and associatedtime) and the immediately previous location are known. In other words,in this usage case, a small trace of user's track is known.

By knowing the current location and the previous location of a user, onehop of user's track is known, but not the whole track. As set forthabove, one hop of the whole track is termed nanotrack herein. Ananotrack is a small part of a user's track, but the entire track of theuser movement cannot be rebuilt from nanotracks since there is no useridentification attached to nanotracks. Thus, embodiments of theinvention prevent the tracking of users based on the collection ofnanotracks because each nanotrack merges with other nanotracks arrivingat the same location. In other words, an individual user is lost in thecrowd. Obviously, there will be no previous location attached to thecurrent location, when no previous location exists.

FIG. 3 shows an example of nanotracks. The rectangles 305 (entitled“Tile”) represent tiles, and the arrows show nanotracks 310, which startin one tile and end in another tile. For example, a user in Tile 9requests a location determination at a first point in time 315. The nextrequest for a location determination from the same user occurs in Tile 8at a later time 320. Thus, nanotrack 325 is formed from this series oflocation determinations.

Illustrative Procedure to Find Demographics:

In one embodiment of the invention, demographics of aggregate anonymoususage at different locations and at different times are determined basedon the flow of users between different locations and demographicsassociated with selected areas (e.g., residential areas).

In one implementation, the techniques disclosed herein are applied whennanotrack for a given percentage of the total number of system users areknown. In such a case, the percentage of user for which nanotracks areknown become a statistical representation of the entire group of users.

The following description is an illustrative implementation of thetechniques for determining the aggregate demographics of a collection ofusers for a given location at a given time. FIG. 5 shows an example oftransitions of users from different locations and different tiles to agiven tile. Meanwhile, FIG. 6 shows an overview of a method 600 ofdetermining the aggregate demographics of a collection of users for agiven location at a given time. A portion of a coverage area 500 isdivided into tiles 505 (only a few rectangular tiles are labeled) (step605). Tiles can have different sizes and/or shapes, or the tiles' sizeand/or shape can change adaptively. Moreover, in certainimplementations, all tiles within a particular area have the same sizeand shape, as explained above. The tiles 505 shown with rectangularboxes in FIG. 5 are of the same size and shape.

Next, a designated period of time of interest is sliced into smallersegments (step 610). In some implementations, the time slices are ofequal size. In other implementations, the lengths of the time slicesvary. Each time slice is one hour over a period of one day is set forthin this illustrative example. However, other time slice durations arewithin the scope of the invention, e.g., multiple hours or a day, one ormore days of a week, etc. Finally, demographic information associatedwith a number of location determination requests is aggregated at thetile level for each segment of time (step 615).

The act of aggregating the demographic information (step 615) is basedon the fact that the aggregate temporal demographics of a tile during atime slice derives from two parts. One part is demographics of residentsof the tile, and the second part is demographics of users who have cometo this tile from other tiles during that time slice. The first part istermed “home demographics” herein, and the corresponding locationestimation requests of those associated with home demographics “homerequests”. The second part is termed “visitor demographics” and thecorresponding location estimation requests associated with visitordemographics are called “visitor requests”. Demographics of usersresiding in the tile are taken from demographic information associatedwith the geographical area of the home area. For example, census data inthe U.S.A. provides a good estimate of the demographics of residents ofdifferent geographical locations in U.S.A. FIG. 4 shows one tile 400,the total location requests of which are divided to two parts, homedemographics 405 and visitor demographics 410.

FIG. 2 depicts nanotracks 205 (transitions between tiles), including thesame tile. Considering all users of the LBS system within a tile at agiven time, nanotracks 205 show a user's movement from one location(e.g., tile 210) to the next (e.g., 215). In other words, the nanotracks205 show from which tile the users transitioned before moving into thetile of interest (tile 215). The number of nanotracks from tile j attime t′ to tile k at time t is shown with T_(jk)(t′,t). Some users mayhave a nanotrack 220 from the same tile. In other words, a nanotrackfrom one time slice of a tile to another time slice of the same tile isalso occurs. FIG. 5 depicts an example of nanotracks 510 for one tile515 in Boston for an hour on Monday morning between 8 am and 9 am.Nanotracks 510 are shown with arrows, which start from previous locationof a user (tile 505) and point to the new location of the user (tile515) determined based on location requests.

The ratio of the residential population to the expected population thattravels to a given tile during a particular time slice is used as anestimate for ratio of home requests to visitor requests. This ratio ofresidential population to the expected population traveled to a tile canbe estimated by, for example, (a) residential to commercial land usedand/or (b) residential to commercial foot-print of real estate.Meanwhile, the ratio of the residential population to the expectedpopulation (residents and visitors) of a tile is shown as “R” here. Theratio of home requests to total requests is a function of time, and itis different at different times of day or night. Thus, the ratio R will,in some instances, have different values within different time slices ofthe time period of interest. The ratio R will vary from 1 to 0.

The demographics of the users making home requests are considered to bethe same as the demographics of the residents of the tile. Not onlyresidents, but also their associates (guests and visitors) are assumedto have the same demographics as the residents (unless other demographicinformation is available for a particular guest or visitor), which, inturn, is the same as the residents of the tile. One way of determiningthe demographics of residents of tiles is using demographics informationthat is available through wide data collection of demographics data bygovernments, e.g., census data in the U.S.A. Residence demographics isrepresented by “D” herein. Therefore, home requests demographics isgoing to be “D”, and the demographic information is treated as constantin between updates of the underlying demographic data (e.g., census dateupdates).

Thus, demographics of a given tile is determined as follows:R(t)D+[1−R(t)]X(t)In the equation above, X(t) is the unknown demographic component ofthose users who traveled to the tile from other tiles at time t (trefers to a time slice) and who made a location determination request.

The total number of nanotracks to tile k at time slice of t, T_(k)(t),can be written as follows:

${T_{k}(t)} = {\sum\limits_{t^{\prime} = {t\; 1}}^{t^{\prime} = t_{Nt}}\;{\sum\limits_{j = 1}^{j = M}\;{T_{jk}\left( {t^{\prime},t} \right)}}}$In which total number of tiles is M, and Nt is total number of timeslices.

Therefore, visitor demographics of tile k, Xk(t) can be found asfollows:

${X_{k}(t)} = {\sum\limits_{t^{\prime} = {t\; 1}}^{t^{\prime} = t_{Nt}}\;{\sum\limits_{j = 1}^{j = M}\;{\frac{T_{jk}\left( {t^{\prime},t} \right)}{T_{k}(t)}\left\lbrack {{R_{j}D_{j}} + {\left( {1 - R_{j}} \right){X_{j}\left( t^{\prime} \right)}}} \right\rbrack}}}$which means the demographics of visitors of tile k is the sum of thedemographics of the users that moved from other tiles to tile kaccording to the ratio of users moved from those tiles relative to allthe users moved to tile k. The ratio of residents to people traveling toa tile can be a function of time as well.

Considering all the tiles, there will be one unknown X(t) for each timeslot of the tile and also there will be an equation to calculate X(t)for each time slot of the tile. For example, if the number of time slotsis N_(t), there will be M times N_(t) number of unknowns and also Mtimes N_(t) number of equations. From this follows the equation below.

${{X_{k}(t)} = {\sum\limits_{t^{\prime} = t_{1}}^{t^{\prime} = t_{Nt}}\;{\sum\limits_{j = 1}^{j = M}\;{\frac{T_{jk}\left( {t^{\prime},t} \right)}{T_{k}(t)}\left\lbrack {{R_{j}D_{j}} + {\left( {1 - R_{j}} \right){X_{j}\left( t^{\prime} \right)}}} \right\rbrack}}}},{k \in \left\lbrack {1,M} \right\rbrack},{t \in \left\lbrack {t_{1},t_{Nt}} \right\rbrack}$

The above equation can also be re-written as follows below.

$M\left\{ {\begin{matrix}{{X_{1}(t)} = {\sum\limits_{t^{\prime} = {t\;}_{1}}^{t^{\prime} = t_{Nt}}\;{\sum\limits_{j = 1}^{j = M}\;{\frac{T_{j\; 1}\left( {t^{\prime},t} \right)}{T_{1}(t)}\left\lbrack {{R_{j}D_{j}} + {\left( {1 - R_{j}} \right){X_{j}\left( t^{\prime} \right)}}} \right\rbrack}}}} \\{{X_{2}(t)} = {\sum\limits_{t^{\prime} = {t\;}_{1}}^{t^{\prime} = t_{Nt}}\;{\sum\limits_{j = 1}^{j = M}\;{\frac{T_{j\; 2}\left( {t^{\prime},t} \right)}{T_{2}(t)}\left\lbrack {{R_{j}D_{j}} + {\left( {1 - R_{j}} \right){X_{j}\left( t^{\prime} \right)}}} \right\rbrack}}}} \\\; \\{{X_{M}(t)} = {\sum\limits_{t^{\prime} = {t\;}_{1}}^{t^{\prime} = t_{Nt}}\;{\sum\limits_{j = 1}^{j = M}\;{\frac{T_{jM}\left( {t^{\prime},t} \right)}{T_{M}(t)}\left\lbrack {{R_{j}D_{j}} + {\left( {1 - R_{j}} \right){X_{j}\left( t^{\prime} \right)}}} \right\rbrack}}}}\end{matrix},{t \in \left\lbrack {t_{1},t_{Nt}} \right\rbrack}} \right.$

The techniques disclosed herein were set forth relative to user requestsfor LBS applications. However, the approach can be applied to anycommunity of users or a group of users for which an analysis is desired.User location estimations can be collected through voluntary use of apositioning system or can be automatically collected. In other words,the method can be applied to any community with known temporal densityin the geographical area of interest with nanotracks.

The techniques described were also concerning only one previouslocation. However, the idea can be extended to include more than oneprevious position. Previous locations can be appended to the currentlocation, optionally, with a limitation on the maximum number ofprevious locations used. Thus, a maximum number (which can bepredefined) of past known locations can be appended to the currentlocation. The last location can also be appended to the current locationwith as many previous locations as possible within a time limit. In suchan implementation case, more than one hop of the user track is known andthe same method can be applied. In such a case, each hop can be treatedas a nanotrack. When more than one hop of a track is known, demographicsof multiple hops can be tied together, because they are coming from thesame user.

In one implementation, when multiple hops of a track are available, thedemographics of a request from a tile can be used for the entire trackfor that user. For example, the tile supplying the demographics use foreach hop of the track can be a user's residence. A tile can beconsidered as the location of user's residence based on an R-value. Forexample, a tile with the highest R-value is considered the user'sresidence. Optionally, to be considered the user's residence, theR-value must be higher than a given threshold. Alliteratively, a tilecan be considered as the location of user's residence based on anR-value and the time of a location estimation request. For example, ifan R-value is relatively high, and the location estimation request ismade at night time or during a weekend, the tile can be considered theuser's residence. Further still, a tile can be considered the user'sresidence tile if a location estimation request was located in anall-residential tile or if a request was located in a tile at the nighttime, and an R value during the night time for the tile indicates it isa residential tile.

Because embodiments of the invention are not limited to nanotracks, itcan be helpful to think of points along the entire track as intermediatestarting and intermediate ending points. In other words, although theuser may make a series of 10 location estimates associated with his orher movements during a given time period, the third location estimatecan be designated as the intermediate starting point, and the seventhlocation estimate can be designated as the intermediate ending point.Thus, if the usage case dictates, the demographics of the tile in whichintermediate starting point occurs (i.e., the third location estimate)can be used as the user's demographic information. Similarly, thisdemographic information can be applied to the tile in which theintermediate ending point occurs (i.e., the seventh location estimate)using the techniques disclosed herein.

Implementations of the described techniques can be employed on, forexample, a WiFi-based Positioning System (WPS) and/or satellitepositioning system that has been deployed on tens of millions ofdevices. For example, many mobile computing devices and smartphones haveWPS and/or GPS capabilities. Moreover, tens of thousands of applicationsavailable for use on the mobile computing devices and/or smartphoneshave aspects that rely on the user's location. Thus, user locationrequests that are generated by these devices and/or applications can becollected to create a density of users in an area of interest, which canbe the entire world. The locations of these users are associated withtheir previous locations to create nanotracks of users (based on thelocation determination requests). The techniques disclosed herein canthen be used to generate temporal demographics about selected geographicareas.

The techniques and systems disclosed herein may be implemented as acomputer program product for use with a computer system or computerizedelectronic device. Such implementations may include a series of computerinstructions, or logic, fixed either on a tangible medium, such as acomputer readable medium (e.g., a diskette, CD-ROM, ROM, flash memory orother memory or fixed disk) or transmittable to a computer system or adevice, via a modern or other interface device, such as a communicationsadapter connected to a network over a medium.

The medium may be either a tangible medium (e.g., optical or analogcommunications lines) or a medium implemented with wireless techniques(e.g., Wi-Fi, cellular, microwave, infrared or other transmissiontechniques). The series of computer instructions embodies at least partof the functionality described herein with respect to the system. Thoseskilled in the art should appreciate that such computer instructions canbe written in a number of programming languages for use with manycomputer architectures or operating systems.

Furthermore, such instructions may be stored in any tangible memorydevice, such as semiconductor, magnetic, optical or other memorydevices, and may be transmitted using any communications technology,such as optical, infrared, microwave, or other transmissiontechnologies.

It is expected that such a computer program product may be distributedas a removable medium with accompanying printed or electronicdocumentation (e.g., shrink wrapped software), preloaded with a computersystem (e.g., on system ROM or fixed disk), or distributed from a serveror electronic bulletin board over the network (e.g., the Internet orWorld Wide Web). Of course, some embodiments of the invention may beimplemented as a combination of both software (e.g., a computer programproduct) and hardware. Still other embodiments of the invention areimplemented as entirely hardware, or entirely software (e.g., a computerprogram product).

Moreover, the techniques and systems disclosed herein can be used with avariety of mobile devices. For example, mobile telephones, smart phones,personal digital assistants, satellite positioning units (e.g., GPSdevices), and/or mobile computing devices capable of receiving thesignals discussed herein can be used in implementations of theinvention. The location estimate, source demographic data, and/ortemporal demographic data can be displayed on the mobile device and/ortransmitted to other devices and/or computer systems. Any or all of theactions for determining the temporal demographic data can be performedon the mobile device. Also, any or all of the actions for determiningthe temporal demographic data can be performed on a server system remotefrom the mobile device based on location determination information aboutthe mobile device. Further, it will be appreciated that the scope of thepresent invention is not limited to the above-described embodiments, butrather is defined by the appended claims; and that these claims willencompass modifications of and improvements to what has been described.

What is claimed is:
 1. A method of estimating demographics associated with a selected geographic area, comprising: for each mobile device of a plurality of mobile devices, associating a more recent location estimate of the mobile device determined by a positioning system that is within the selected geographic area with a previous location estimate of the mobile device determined by the positioning system, and determining an origin geographic area that includes the previous location estimate; estimating demographics associated with the selected geographic area, by a computer system, based at least in part on demographics associated with the origin geographic areas of the plurality of mobile devices; and transmitting the estimated demographics to at least one other computer system.
 2. The method of claim 1, further comprising: dividing a coverage area of the positioning system into a plurality of geographic areas, wherein the selected geographic area and the origin geographic areas are ones of the plurality of geographic areas.
 3. The method of claim 2, wherein the plurality of geographic areas each have a same size and shape.
 4. The method of claim 1, further comprising: dividing a designated time period used for estimating the demographics associated with the selected geographic area into a plurality of time slices, wherein the more recent location estimates were performed during a different time slice than the previous location estimates of the plurality of mobile devices.
 5. The method of claim 4, wherein the estimated demographics are associated with a time slice during which the more recent location estimates were performed.
 6. The method of claim 1, wherein the more recent location estimate and the previous location estimate of a given mobile device of the plurality of mobile devices form a portion of a sequence of location estimates for the given mobile device.
 7. The method of claim 6, wherein the previous location estimate of the given mobile device is immediately prior to the more recent location estimate of the given mobile device in the sequence of location estimates of the given mobile device.
 8. The method of claim 1, wherein the positioning system comprises a WiFi-based positioning system.
 9. The method of claim 1, wherein the demographics associated with the origin geographic areas of the plurality of mobile devices are visitor demographics, and the estimating demographics associated with the selected geographic area is based on a combination of the visitor demographics and home demographics of one or more mobile devices whose users are residents of the selected geographic area.
 10. The method of claim 9, further comprising: combining the home demographics and the visitor demographics according to a ratio of mobile devices transiting into the selected geographic area versus mobile devices whose users are residents of the selected geographic area.
 11. A method of estimating demographics associated with a selected geographic area, comprising: identifying a plurality of mobile devices that are within the selected geographic area based on location requests from the plurality of mobile devices to a positioning system; determining home demographics associated with one or more of the plurality of mobile devices whose users are residents of the selected geographic area; determining visitor demographics associated with one or more of the plurality of mobile devices whose users are transiting into the selected geographic area, the determining visitor demographics performed at least in part by determining an origin geographic area of each of one or more of the mobile devices whose users are transiting into the selected geographic area, and obtaining demographics associated with each origin geographic area; estimating demographics associated with the selected geographic area, by a computer system, based on a combination of the home demographics and the visitor demographics; and transmitting the estimated demographics to at least one other computer system.
 12. The method of claim 11, wherein the estimating further comprises: determining a ratio of the mobile devices transiting into the selected geographic area versus the mobile devices whose users are residents of the selected geographic area; and combining the home demographics and the visitor demographics according to the ratio.
 13. The method of claim 11, wherein the positioning system comprises a WiFi-based positioning system.
 14. A non-transitory computer readable medium storing instructions for estimating demographics associated with a selected geographic area, the instructions when executed on one or more processors operable to: for each mobile device of a plurality of mobile devices, associate a more recent location estimate of the mobile device determined by a positioning system that is within the selected geographic area with a previous location estimate of the mobile device determined by the positioning system, and determine an origin geographic area in which the previous location estimate was located; and estimate demographics associated with the selected geographic area based at least in part on demographics associated with the origin geographic areas of the plurality of mobile devices.
 15. The non-transitory computer readable medium of claim 14, wherein the instructions when executed are further operable to: divide a coverage area of the positioning system into a plurality of geographic areas, wherein the selected geographic area and the origin geographic areas of the plurality of mobile devices are ones of the plurality of geographic areas.
 16. The non-transitory computer readable medium of claim 14, wherein the instructions when executed are further operable to: divide a designated time period used for estimating the demographics associated with the selected geographic area into a plurality of time slices, wherein the more recent location estimates were performed during a different time slice than the previous location estimates of the plurality of mobile devices.
 17. The non-transitory computer readable medium of claim 14, wherein the more recent location estimates and the previous location estimate of a given mobile device of the plurality of mobile devices form a portion of a sequence of location estimates for the given mobile device.
 18. The non-transitory computer readable medium of claim 17, wherein the previous location estimate of the given mobile device is immediately prior to the more recent location estimate of the given mobile device in the sequence of location estimates of the given mobile device.
 19. The non-transitory computer readable medium of claim 14, wherein the positioning system comprises a WiFi-based positioning system.
 20. The non-transitory computer readable medium of claim 14, wherein the demographics associated with the origin geographic areas of the plurality of mobile devices are visitor demographics, and the estimating demographic information associated with the selected geographic area is based on a combination of the visitor demographics and home demographics of one or more mobile devices whose users are residents of the selected geographic area.
 21. A system comprising: software executable on a plurality of mobile devices configured to collect location determination requests and utilize a positioning system to produce location estimates of the mobile devices; and a server configured to receive the location estimates of the plurality of mobile devices from the positioning system and based thereon to: for each mobile device of the plurality of mobile devices, associate a more recent location estimate of the mobile device that is within a first geographic area with a previous location estimate of the mobile device, determine an origin geographic area that includes the previous location estimate, and estimate demographics associated with the first geographic area based at least in part on demographics associated with the origin geographic areas of the plurality of mobile devices.
 22. The system of claim 21, wherein the positioning system comprises a WiFi-based positioning system. 